Absorption. Despite an age-related decrease in small-bowel surface area, slowed gastric emptying, and an increase in gastric pH, changes in drug absorption tend to be clinically inconsequential for most drugs.
2. Which pharmacokinetic/pharmacodynamic parameter does the aging process least affect? There is no conclusive evidence that the absorptive process is changed appreciably in older adults. Distribution, metabolism, and excretion are all affected significantly by aging.
As ageing is associated with some reduction in first-pass metabolism, bioavailability of a few drugs can be increased. With ageing body fat increases and total body water as well as lean body mass decrease.
Drug distribution is affected by the changes in body composition associated with age due to an increase in body fat percentage and decrease in lean muscle mass. There is also a decrease in total body water.
Aging results in a number of significant changes in the human liver including reductions in liver blood flow, size, drug-metabolizing enzyme content, and pseudocapillarization. Drug metabolism is also influenced by comorbid disease, frailty, concomitant medicines, and (epi)genetics.
Which pharmacokinetic/pharmacodynamic parameter is least affected by the aging process? There is no conclusive evidence that the absorptive process is changed appreciably in older adults. Distribution, metabolism, and excretion are all affected significantly by aging.
One of the most important pharmacokinetic changes associated with aging is decreased renal elimination of drugs. Maintenance of normal serum creatinine levels can mislead clinicians to assume those levels reflect normal kidney function. Decreases in tubular function with age parallel those in glomerular function.
Pharmacokinetics can vary from person to person and it is affected by age, gender, diet, environment, body weight and pregnancy, patient’s pathophysiology, genetics and drug- drug or food-drug interactions. Drug therapy is impacted by factors that affect pharmacokinetics and pharmacodynamics.
There are four main components of pharmacokinetics: liberation, absorption, distribution, metabolism and excretion (LADME). These are used to explain the various characteristics of different drugs in the body.
As we age, physiological changes can affect the way our body metabolises drugs, causing adverse reactions. Older people are more likely to be taking multiple medications (‘polypharmacy’), which increases the risk of medications being implicated in hospital admissions.
Age-related changes that impact bioavailability of a medication include: Decreased blood flow to the digestive tract. Increased oxygen levels in the blood. Decreased subcutaneous fat.
As age increases, the functions of tissues and organs in the body gradually decline. Due to this decline in organ function, drug absorption, distribution, metabolism and excretion (ADME processes) in elderly people are worse than those of young people.
Pharmacokinetic changes include a reduction in renal and hepatic clearance and an increase in volume of distribution of lipid soluble drugs (hence prolongation of elimination half-life) whereas pharmacodynamic changes involve altered (usually increased) sensitivity to several classes of drugs such as anticoagulants,